US10880958B2 - Induction heating device and induction heating method - Google Patents

Induction heating device and induction heating method Download PDF

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US10880958B2
US10880958B2 US16/069,453 US201616069453A US10880958B2 US 10880958 B2 US10880958 B2 US 10880958B2 US 201616069453 A US201616069453 A US 201616069453A US 10880958 B2 US10880958 B2 US 10880958B2
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conductor plate
coil
induction heating
plate
heating device
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US20190029080A1 (en
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Kenji Umetsu
Tsutomu Ueki
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Nippon Steel Corp
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Nippon Steel Corp
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/10—Induction heating apparatus, other than furnaces, for specific applications
    • H05B6/101—Induction heating apparatus, other than furnaces, for specific applications for local heating of metal pieces
    • H05B6/103—Induction heating apparatus, other than furnaces, for specific applications for local heating of metal pieces multiple metal pieces successively being moved close to the inductor
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/10—Induction heating apparatus, other than furnaces, for specific applications
    • H05B6/101—Induction heating apparatus, other than furnaces, for specific applications for local heating of metal pieces
    • H05B6/103—Induction heating apparatus, other than furnaces, for specific applications for local heating of metal pieces multiple metal pieces successively being moved close to the inductor
    • H05B6/104—Induction heating apparatus, other than furnaces, for specific applications for local heating of metal pieces multiple metal pieces successively being moved close to the inductor metal pieces being elongated like wires or bands
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/34—Methods of heating
    • C21D1/42—Induction heating
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/36—Coil arrangements
    • H05B6/362—Coil arrangements with flat coil conductors
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/36—Coil arrangements
    • H05B6/365—Coil arrangements using supplementary conductive or ferromagnetic pieces
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/36—Coil arrangements
    • H05B6/42—Cooling of coils
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/36—Coil arrangements
    • H05B6/44—Coil arrangements having more than one coil or coil segment
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/25—Process efficiency

Definitions

  • the present invention relates to an induction heating device and an induction heating method.
  • the induction heating device is to apply alternating magnetic fields generated from coils to the conductor plate, generate, in this conductor plate, Joule heat based on eddy currents induced in this conductor plate by electromagnetic induction, and heat this conductor plate by this Joule heat.
  • Examples of such an induction heating device include a LF (Longitudinal Flux)-type induction heating device and a TF (Transverse Flux)-type induction heating device.
  • LF Longitudinal Flux
  • TF Transverse Flux
  • FIG. 12 is a view illustrating a constitution of the LF-type induction heating device.
  • FIG. 12 is a view illustrating the state of a LF-type induction heating device 1200 viewed from above.
  • X-Y-Z coordinates in each drawing indicate the directional relationship in each drawing.
  • the origins of X-Y-Z coordinates in the respective drawings are the same (the origin of X-Y-Z coordinates is not limited to the position illustrated in each drawing).
  • a band-shaped conductor plate S to be heated is to be passed in a positive direction of the Y axis (in an outline arrow direction in FIG. 12 ). The above is applied also to the other drawings.
  • the LF-type induction heating device 1200 illustrated in FIG. 12 includes a solenoid coil 1210 .
  • the solenoid coil 1210 is wound in a direction substantially vertical to the passing direction of the conductor plate S so as to surround the band-shaped conductor plate S.
  • a path of current to flow through the solenoid coil 1210 and the conductor plate S to be passed are interlinked.
  • one example of the direction of the current flowing through the solenoid coil 1210 is the direction of an arrow line illustrated in the solenoid coil 1210 in FIG. 12 .
  • the conductor plate is passed through the inside of the solenoid coil in an interlinked state. For this reason, in the case where the conductor plate is inside the solenoid coil, it is impossible to retract the solenoid coil temporarily. For example, when the conductor plate fractures on the upstream side from the induction heating device, the conductor plate is passed through the induction heating device while fluttering. In this case, the conductor plate comes into contact with the coil, and the coil and the like are liable to be damaged. Further, the coil itself often becomes an obstacle to a restoration work when the conductor plate is passed through a line when the operation resumes.
  • Patent Literature 2 discloses a technique in which a part region of a coil is set as a door portion and the door portion is designed to be able to open and close with respect to a coil main body. Using the technique described in Patent Literature 2 enables retraction even in the LF-type induction heating device by horizontally moving the coil after the door portion is opened with respect to the coil main body.
  • FIG. 13 is a view illustrating a constitution of the TF-type induction heating device. Concretely, FIG. 13 is a view illustrating the state of a TF-type induction heating device 1300 viewed from above.
  • two coils 1310 , 1320 are arranged above and below a conductor plate S across a plate surface of the band-shaped conductor plate S.
  • the two coils 1310 , 1320 are turned in a direction substantially parallel to the plate surface of the conductor plate S.
  • paths of currents to flow through the two coils 1310 , 1320 and the conductor plate S to be passed do not interlink.
  • one example of the direction of the current flowing through the coils 1310 , 1320 is the direction of an arrow line illustrated in the coils 1310 , 1320 in FIG. 13 .
  • Alternating currents which are the same in direction, are applied to the two coils 1310 , 1320 and alternating magnetic fields are applied substantially vertically to the plate surface of the conductor plate S (such a magnetic field is called a transverse magnetic field (TF)).
  • TF transverse magnetic field
  • the alternating magnetic fields which are the same in direction, are generated from the coils 1310 , 1320 .
  • the conductor plate S can be heated to a higher temperature.
  • Patent Literature 3 discloses a technique in which two single-turn induction heating coils arranged across a conductor plate are shifted in a passing direction of the conductor plate by a coil width.
  • the two single-turn induction heating coils described in Patent Literature 3 play the same role as that of the coils 1310 , 1320 .
  • the alternating currents to be applied to the coils 1310 , 1320 are the same in direction.
  • alternating currents to be applied to the two single-turn induction heating coils described in Patent Literature 3 are opposite in direction.
  • the two single-turn induction heating coils are shifted in the passing direction of the conductor plate by a coil width, and thereby an offset of eddy currents generated in the conductor plate due to transverse magnetic fields from the two single-turn induction heating coils is suppressed.
  • the eddy current concentrates in width-direction end portions of the conductor plate S (in the following explanation, these portions are referred to as edge portions as necessary). Therefore, it is general that these edge portions are overheated.
  • conductor plates 1330 to 1360 are arranged (see Patent Literature 4).
  • Patent Literature 5 discloses a technique in which not a conductor plate but coils are arranged.
  • Primary coils are arranged above and below a conductor plate across the conductor plate.
  • the primary coils are heating coils and play the same role as that of the coils 1310 , 1320 .
  • a plurality of secondary coils are provided between the conductor plate and the primary coil.
  • the plural secondary coils play a role of weakening, out of primary magnetic fluxes generated from the primary coils, the primary magnetic fluxes in the vicinity of edge portions of the conductor plate and reducing eddy currents themselves flowing through the conductor plate.
  • the plural secondary coils are designed to be movable along the plate surface direction of the conductor plate.
  • the present invention has been made in consideration of the above problems, and an object thereof is to provide an induction heating device that achieves both things, which are to uniformize a temperature distribution in a width direction of a conductor plate as much as possible and to retract coils temporarily, without adding a special constitution.
  • An induction heating device is an induction heating device that inductively heats a passing conductor plate, the induction heating device including; a first coil that generates a magnetic field in a plate thickness direction of the conductor plate by an alternating current flowing therethrough; and a second coil that generates a magnetic field in the plate thickness direction of the conductor plate by an alternating current flowing therethrough, in which the first coil and the second coil are positioned to sandwich the conductor plate therebetween, the first coil and the second coil are substantially the same in position in a passing direction of the conductor plate, magnetic fields that are opposite to each other in direction are generated in the plate thickness direction of the conductor plate from the first coil and the second coil by the alternating currents, eddy currents are generated inside the conductor plate by the magnetic fields that are opposite in direction, and the conductor plate is inductively heated by the eddy currents.
  • An induction heating method is an induction heating method to, by using an induction heating device including: a first coil that generates a magnetic field in a plate thickness direction of a conductor plate by an alternating current flowing therethrough; and a second coil that generates a magnetic field in the plate thickness direction of the conductor plate by an alternating current flowing therethrough, in which the first coil and the second coil are positioned to sandwich the conductor plate therebetween, and the first coil and the second coil are substantially the same in position in a passing direction of the conductor plate, inductively heat the passing conductor plate, the method including: generating magnetic fields that are opposite to each other in direction in the plate thickness direction of the conductor plate from the first coil and the second coil by the alternating currents; generating eddy currents inside the conductor plate by the magnetic fields opposite in direction; and inductively heating the conductor plate by the eddy currents.
  • an induction heating device that achieves both things, which are to uniformize a temperature distribution in a width direction of a conductor plate as much as possible and to retract coils temporarily, without adding a special constitution.
  • FIG. 1 is a view illustrating one example of a constitution of an induction heating system.
  • FIG. 2 is a view illustrating one example of a Y-Z cross section of an induction heating device in an embodiment.
  • FIG. 3 is a view conceptually illustrating one example of directions of magnetic fields generated by alternating currents flowing through a first coil and a second coil.
  • FIG. 4 is a view conceptually illustrating one example of the state where the magnetic fields generated by the alternating currents flowing through the first coil and the second coil penetrate into a conductor plate.
  • FIG. 5A is a view conceptually illustrating one example of eddy currents assuming that an eddy current based on the magnetic field generated by the first coil and an eddy current based on the magnetic field generated by the second coil exist independently.
  • FIG. 5B is a view conceptually illustrating one example of eddy currents generated inside the conductor plate.
  • FIG. 6 is a view illustrating one example of a distribution of surface temperatures of the conductor plate in a width direction.
  • FIG. 7 is a view conceptually illustrating one example of the relationship between a position of the conductor plate in a plate thickness direction and current densities of the eddy currents flowing through the conductor plate.
  • FIG. 8 is a view illustrating a first modified example of the constitution of the induction heating system.
  • FIG. 9 is a view illustrating a second modified example of the constitution of the induction heating system.
  • FIG. 10 is a view illustrating a third modified example of the constitution of the induction heating system.
  • FIG. 11 is a view illustrating one example of a Y-Z cross section of an UF-type induction heating device in the third modified example.
  • FIG. 12 is a view illustrating a constitution of a LF-type induction heating device.
  • FIG. 13 is a view illustrating a constitution of a TF-type induction heating device.
  • FIG. 1 is a view illustrating one example of a constitution of an induction heating system.
  • FIG. 1 is a view illustrating the state of an induction heating device 100 viewed from above.
  • the induction heating device 100 is referred to as an UF (Ulterior Flux)-type induction heating device as necessary.
  • UF Ultraviolet Flux
  • the type of the induction heating device 100 in this embodiment is referred to as an UF type.
  • the conductor plate S is a steel plate, for example.
  • the conductor plate S is not limited to the steel plate. It is possible to set conductor plates such as a non-magnetic metal plate and a ferromagnetic metal plate to a heating target. Plating may be applied to a surface of the metal plate, and a plurality of metal plates may be laminated. Further, the thickness of the conductor plate S is not limited in particular. It is possible to set a conductor sheet having a thickness of 1 [mm] or less, for example, (thin sheet) to a heating target.
  • the direction of the Y axis in FIG. 1 is not limited in particular, and may be a direction horizontal to the ground, or a direction vertical to the ground, for example.
  • the induction heating system includes the UF-type induction heating device 100 and an alternating-current power supply 200 .
  • the UF-type induction heating device 100 includes the first coil 110 , the second coil 120 , a first core 130 , and a second core 140 . Further, the alternating-current power supply 200 is electrically connected to the first coil 110 and the second coil 120 .
  • the first coil 110 and the second coil 120 are coils that are the same in material, shape, and size.
  • the first coil 110 and the second coil 120 each are formed of a metal such as copper, for example.
  • the first coil 110 is a coil turned in a direction substantially parallel to the plate surface of the conductor plate S.
  • the first coil 110 is arranged so as to have a surface that is made of turned portions thereof (what is called a coil surface thereof) substantially face one surface (front surface) of the two plate surfaces of the conductor plate S at such a distance as not to be in contact with the conductor plate S.
  • the second coil 120 is also a coil turned in a direction substantially parallel to the plate surface of the conductor plate S similarly to the first coil 110 .
  • the second coil 120 is arranged so as to have a surface that is made of turned portions thereof (what is called a coil surface thereof) substantially face the other surface (rear surface) of the two plate surfaces of the conductor plate S at such a distance as not to be in contact with the conductor plate S.
  • upper end surfaces and lower end surfaces of the first coil 110 and the second coil 120 when viewed along a passing direction of the conductor plate S (Y-axis direction in the example illustrated in FIG. 1 ) are flat surfaces. Further, these surfaces are substantially parallel to the plate surface of the conductor plate S.
  • first coil 110 and the second coil 120 are arranged at the positions where the first coil 110 and the second coil 120 substantially face each other across the conductor plate S. That is, the positions of the first coil 110 and the second coil 120 in the Y-axis direction (passing direction of the conductor plate S) are substantially the same.
  • the example illustrated in FIG. 1 is set that the distance between the first coil 110 and the conductor plate S and the distance between the second coil 120 and the conductor plate S are the same.
  • the number of turns of the first coil 110 and the number of turns of the second coil 120 are both one [time]. As above, in the example illustrated in FIG.
  • the positions of the first coil 110 other than the position of the Z-axis direction and the positions of the second coil 120 other than the position of the Z-axis direction are substantially the same.
  • the first coils 110 , the second coil 120 can be fabricated by the same constitution as that of the coils 1310 , 1320 illustrated in FIG. 13 .
  • FIG. 2 is a view illustrating one example of a Y-Z cross section of the UF-type induction heating device 100 .
  • the Y-Z cross section is a cross section in the case of cutting the UF-type induction heating device 100 at the middle position in a width direction (X-axis direction) of the conductor plate S along a surface determined by the passing direction of the conductor plate S (Y-axis direction) and a plate thickness direction (Z-axis direction) (Y-Z plane).
  • the first core 130 and the second core 140 are cores that are the same in material, shape, and size.
  • the first core 130 and the second core 140 are each formed of a soft magnetic material such as ferrite, for example.
  • the first core 130 is arranged at the position to be a magnetic path of magnetic fluxes generated from the first coil 110 .
  • the second core 140 is arranged at the position to be a magnetic path of magnetic fluxes generated from the second coil 120 .
  • the first core 130 has a shape obtained by forming recessed portions in a rectangular parallelepiped shape according to shapes of regions extending in the width direction (X-axis direction) of the first coil 110 .
  • the recessed portions of the first core 130 are formed so that in the case where the first coil 110 is arranged in the recessed portions, the surface of the first coil 110 facing the conductor plate S and the surface of the first core 130 facing the conductor plate S become substantially flush with each other.
  • the second core 140 has a shape obtained by forming recessed portions in a rectangular parallelepiped shape according to shapes of regions extending in the width direction (X-axis direction) of the second coil 120 . Further, the recessed portions of the second core 140 are formed so that in the case where the second coil 120 is arranged in the recessed portions, the surface of the second coil 120 facing the conductor plate S and the surface of the second core 140 facing the conductor plate S become substantially flush with each other.
  • the shapes of the first coil 110 and the second coil 120 are not limited to the shapes illustrated in FIG. 1 .
  • the surface of the first coil 110 facing the conductor plate S and the surface of the first core 130 facing the conductor plate S do not need to be substantially flush with each other.
  • an insulating treatment is performed between the first coil 110 and the first core 130 .
  • An insulating treatment is performed also between the second coil 120 and the second core 140 .
  • the first coil 110 and the second coil 120 each have a hollow shape, as illustrated in FIG. 2 .
  • the first coil 110 and the second coil 120 each have a hollow rectangle in a cross section vertical to the direction in which the alternating current flows.
  • a cooling water is made to flow through the hollow portions. This cooling water water-cools the first coil 110 and the second coil 120 , thereby making it possible to suppress increases in heat generation of the first coil 110 and the second coil 120 .
  • the conductor plate S is passed so as to have an entire region thereof in the width direction (X-axis direction) positioned between the first core 130 and the second core 140 . That is, the conductor plate S is designed to pass through between the first coil 110 and the second coil 120 in a state where its end portions (edge portions) in the width direction are positioned on the inner side relative to width-direction (X-axis-direction) end portions of the first core 130 and the second core 140 .
  • Lengths in the width direction (X-axis direction) of the UF-type induction heating device 100 are determined beforehand so as to achieve the above.
  • one end portion 111 of the first coil 110 is electrically connected to one terminal 201 of two output terminals of the alternating-current power supply 200 . Further, the other end portion 112 of the first coil 110 is electrically connected to the other terminal 202 of the two output terminals of the alternating-current power supply 200 .
  • one end portion 121 positioned at a position facing the other end portion 112 of the first coil 110 each other in the Z-axis direction is electrically connected to the one terminal 201 of the two output terminals of the alternating-current power supply 200 .
  • the other end portion 122 positioned at a position facing the one end portion 111 of the first coil 110 each other in the Z-axis direction is electrically connected to the other terminal 202 of the two output terminals of the alternating-current power supply 200 .
  • the first coil 110 and the second coil 120 are connected in parallel to the alternating-current power supply 200 so that turning directions of the first coil 110 and the second coil 120 (when viewed from the alternating-current power supply 200 ) become opposite to each other.
  • the directions (when viewed from the same viewpoint at the same time) of the alternating currents flowing through the mutually facing regions of the first coil 110 and the second coil 120 become opposite to each other (see arrow lines illustrated in the first coil 110 and the second coil 120 in FIG. 1 ).
  • the arrow lines illustrated in the first coil 110 and the second coil 120 in FIG. 1 indicate that in the case of the UF-type induction heating device 100 being viewed from above, the direction of the alternating current flowing through the first coil 110 is clockwise (right-handed) and the direction of the alternating current flowing through the second coil 120 is counterclockwise (left-handed).
  • the alternating currents applied to the first coil 110 and the second coil 120 from the alternating-current power supply 200 are different only in direction (when viewed from the same viewpoint at the same time), and are the same in magnitude and frequency (at the same time).
  • a waveform of the alternating current is a sine wave, for example.
  • the waveform of the alternating current is not limited to the sine wave, and can be set to the same waveform as that which can be used in a general induction heating device.
  • the directions (at the same time) of the alternating currents flowing through the mutually facing regions of the first coil 110 and the second coil 120 are referred to as “the directions of the alternating currents of the first coil 110 and the second coil 120 ” as necessary.
  • FIG. 3 is a view conceptually illustrating one example of the directions of magnetic fields generated by the alternating currents flowing through the first coil 110 and the second coil 120 .
  • FIG. 3 illustrations of the hollow portions of the first coil 110 and the second coil 120 are omitted similarly to FIG. 1 .
  • the directions of magnetic fields in the case where the alternating currents flow in the directions of the arrow lines illustrated in the first coil 110 and the second coil 120 in FIG. 1 will be described as an example.
  • the conductor plate S is illustrated with a thicker thickness as compared to the other drawings.
  • the alternating current flows through the first coil 110 , and thereby a magnetic field H 1 in a direction substantially vertical to the plate surface of the conductor plate S (namely, in the plate thickness direction of the conductor plate S) is generated in the region between the first core 130 and the conductor plate S.
  • the alternating current flows through the second coil 120 , and thereby a magnetic field H 2 in a direction substantially vertical to the plate surface of the conductor plate S (namely, in the plate thickness direction of the conductor plate S) is generated in the region between the second core 140 and the conductor plate S.
  • the directions of the alternating currents flowing through the first coil 110 and the second coil 120 are set opposite to each other, and thus as illustrated in FIG.
  • the directions of the currents flowing through the coils 1310 , 1320 are set the same.
  • the two single-turn induction heating coils are shifted in the passing direction of the conductor plate by a coil width in order to prevent an offset of eddy currents generated in the conductor plate due to the transverse magnetic fields from the two single-turn induction heating coils.
  • the directions of the alternating currents flowing through the first coil 110 and the second coil 120 are set opposite to each other, and at the same time, the positions of the first coil 110 and the second coil 120 in the Y-axis direction (passing direction of the conductor plate S) are set substantially the same.
  • the magnetic fields penetrating the conductor plate make eddy currents flow through the conductor plate, and these eddy currents heat the conductor plate.
  • the directions of the currents to be applied to the two coils are set the same.
  • the conductor plate is arranged between the two coils and the currents at a frequency employed in the TF-type induction heating device are applied to these two coils in the opposite directions, and thereby magnetic fields generated by the coils are offset even in the conductor plate.
  • the eddy currents are not generated in the conductor plate and the conductor plate is not inductively heated.
  • the magnetic fields generated by the two coils are increased in magnitude, thereby making it possible to heat the conductor plate to high temperature. Accordingly, applying the alternating currents to these coils so as to cancel the magnetic fields generated by these two coils leads to a reduction in effects of the TF-type induction heating device.
  • Patent Literature 3 is based on the idea that the eddy currents generated in the conductor plate by the magnetic fields from the two single-turn induction heating coils are offset unless the single-turn induction heating coils are shifted in the passing direction of the conductor plate. Then, like the technique described in Patent Literature 3, in the constitution in which the two single-turn induction heating coils are shifted in the passing direction of the conductor plate by a coil width, overheating of the edge portions occurs unless the techniques described in Patent Literatures 4, 5 are applied. Further, the two single-turn induction heating coils assist the LF-type induction heating device, and fail to inductively heat the conductor plate up to a desired temperature by themselves.
  • the conductor plate S is arranged between the first coil 110 and the second coil 120 in a state where the positions of the first coil 110 and the second coil 120 in the Y-axis direction (passing direction of the conductor plate S) are made substantially the same, as long as the frequency of the alternating currents to be applied to the first coil 110 and the second coil 120 is adjusted even though the directions of the alternating currents flowing through the first coil 110 and the second coil 120 are made opposite to each other, the inside of the conductor plate S is brought into a state where the magnetic fields H 1 , H 2 generated by the alternating currents flowing through the first coil 110 and the second coil 120 are not offset, and the eddy currents based on the magnetic fields H 1 , H 2 are generated inside the conductor plate S.
  • FIG. 4 is a view conceptually illustrating one example of the state where the magnetic fields H 1 , H 2 generated by the alternating currents flowing through the first coil 110 and the second coil 120 penetrate into the conductor plate S.
  • a distribution of currents generated in the conductor plate by electromagnetic induction has a property in which the current leans toward the surface by a skin effect, and this tendency is increased as the frequency is higher.
  • ⁇ [m] is expressed by (1) Expression below.
  • ⁇ resistivity of the conductor [ ⁇ m]
  • ⁇ magnetic permeability of the conductor [H/m]
  • ⁇ s is relative permeability of the conductor [ ⁇ ]
  • f is a frequency f [Hz].
  • the values of the magnetic permeability ⁇ (relative permeability ⁇ s ) and the resistivity ⁇ are values of the conductor plate S at a target heating temperature mainly.
  • the present inventors found out that based on (1) Expression above, the frequency of the alternating currents to be applied to the first coil 110 and the second coil 120 (f in (1) Expression) is adjusted, and thereby the magnetic fields generated by the alternating currents flowing through the first coil 110 and the second coil 120 are not offset inside the conductor plate S even when in a state where the positions of the first coil 110 and the second coil 120 in the Y-axis direction (passing direction of the conductor plate S) are made substantially the same, the conductor plate S is arranged between the first coil 110 and the second coil 120 and the directions of the alternating currents flowing through the first coil 110 and the second coil 120 are made opposite to each other.
  • the present inventors found out the following range. That is, the present inventors found out that it is preferred to determine the frequency of the alternating currents to be applied to the first coil 110 and the second coil 120 (f in (1) Expression) in a range satisfying (2) Expression below. ⁇ d/ 2 (2)
  • d is a plate thickness [m] of the conductor plate S.
  • d is a plate thickness [m] of the conductor plate S.
  • the eddy currents Ie 1 , Ie 2 which are opposite to each other in direction, appear separately.
  • the eddy current Ie 1 can heat one surface side of the conductor plate S
  • the eddy current Ie 2 can heat the other surface side of the conductor plate S.
  • the directions of the eddy currents Ie 1 , Ie 2 illustrated in FIG. 4 are one example, and as illustrated in FIG. 5B that will be described later, there are also a region where the direction of the eddy current Ie 1 is opposite to the direction illustrated in FIG. 4 and a region where the direction of the eddy current Ie 2 is opposite to the direction illustrated in FIG. 4 .
  • the upper limit value of the frequency of the alternating currents to be applied to the first coil 110 and the second coil 120 is not limited in particular, and is set appropriately as usage.
  • a frequency as low as possible only needs to be selected within the range satisfying (1) Expression.
  • a high frequency only needs to be selected according to the thickness from the surface of the region desired to be heated (a high frequency only needs to be selected as the range in the thickness direction from the surface is smaller as a range desired to be heated).
  • FIG. 5A and FIG. 5B are views each explaining one example of the eddy currents generated inside the conductor plate S.
  • FIG. 5A is a view conceptually illustrating one example of the eddy currents assuming that the eddy current based on the magnetic field H 1 generated by the alternating current flowing through the first coil 110 and the eddy current based on the magnetic field H 2 generated by the alternating current flowing through the second coil 120 exist independently.
  • FIG. 5B is a view conceptually illustrating one example of the eddy currents generated inside the conductor plate S. In FIG. 5A and FIG. 5B , there is illustrated only a portion of the conductor plate S near a region (between the first coil 110 and the second coil 120 ) inside the UF-type induction heating device 100 .
  • FIG. 5A and FIG. 5B there are described, as an example, the eddy currents generated in the case where the alternating currents flow through the first coil 110 and the second coil 120 in the directions illustrated in FIG. 1 . That is, the direction of the magnetic field H 1 generated by the alternating current flowing through the first coil 110 is a negative direction of the Z axis. Further, the direction of the magnetic field H 2 generated by the alternating current flowing through the second coil 120 is a positive direction of the Z axis. Further, in FIG. 5A and FIG. 5B , it is set that the alternating current at the frequency f satisfying (1) Expression flows through the first coil 110 and the second coil 120 .
  • an eddy current I 1 based on the magnetic field H 1 generated by the alternating current flowing through the first coil 110 flows in a direction to cancel the magnetic field H 1 (see FIG. 5A ).
  • an eddy current I 2 based on the magnetic field H 2 generated by the alternating current flowing through the second coil 120 flows in a direction to cancel the magnetic field H 2 (see FIG. 5A ).
  • These eddy currents I 1 and I 2 are generated independently in response to the magnetic fields H 1 and H 2 respectively.
  • the conductor in a region apart from the width-direction (X-axis-direction) end portions (edge portions) of the conductor plate S, the conductor (forming the conductor plate S) exists around the region (the conductor plate S exists continuously in the passing direction (Y-axis direction). Accordingly, the eddy currents in this region out of the eddy currents I 1 , I 2 remain separated and exist without mixing with each other.
  • the eddy currents actually generated in the conductor plate out of the eddy currents I 1 , I 2 illustrated in FIG. 5A result in only the eddy currents existing in the region (surface) vertical to the passing direction (Y-axis direction) of the conductor plate S. That is, the eddy currents along the width-direction (X-axis-direction) end portions (edge portions) of the conductor plate S are not generated. As a result, as illustrated in FIG.
  • the eddy current Ie 1 and the eddy current Ie 2 flow in directions opposite to each other through the one surface (upper surface) and the other surface (lower surface) of the conductor plate S respectively.
  • FIG. 5B (loops of) the eddy currents Ie 1 , Ie 2 opposite to each other in direction are generated in two regions apart from each other in the passing direction (Y-axis direction) of the conductor plate S, which are the regions (surfaces) inside the conductor plate S vertical to the passing direction (Y-axis direction) of the conductor plate S.
  • the present inventors obtained the findings that in the case where the alternating currents opposite to each other in direction are applied to the first coil 110 and the second coil 120 , even when the magnetic fields (transverse magnetic fields) are generated in the direction vertical to the plate surface of the conductor plate S from the first coil 110 and the second coil 120 similarly to the TF-type induction heating device, the eddy currents Ie 1 , Ie 2 flow through the regions (surfaces) vertical to the passing direction (Y-axis direction) of the conductor plate S similarly to the LF-type induction heating device.
  • eddy currents Ie 1 , Ie 2 do not flow through the width-direction (X-axis-direction) end portions (edge portions) of the conductor plate S along the longitudinal direction (Y-axis direction). Accordingly, like the TF-type induction heating device, the edge portions are not overheated. Thus, it is possible to make the temperature distribution in the width direction (X-axis direction) of the conductor plate S substantially uniform. Furthermore, the directions of the eddy currents Ie 1 , Ie 2 flowing through the conductor plate S are opposite to each other.
  • the single induction heating device makes it possible to generate the eddy currents equivalent to the eddy currents generated in the two LF-type induction heating devices.
  • first coil 110 and the second coil 120 can be fabricated by the same coils as those in the TF-type induction heating device. Accordingly, similarly to the TF-type induction heating device, for example, only moving the first coil 110 and the second coil 120 makes it possible to retract the UF-type induction heating device 100 temporarily.
  • the first method there can be cited a method of moving the first coil 110 and the second coil 120 in the horizontal direction until the UF-type induction heating device 100 no longer faces the plate surface of the conductor plate S each other.
  • first coil 110 and the second coil 120 are moved in the same direction. That is, the first coil 110 and the second coil 120 are moved in the positive direction or the negative direction of the X axis.
  • first coil 110 and the second coil 120 in different directions. That is, the first coil 110 is moved in the negative direction of the X axis, and the second coil 120 is moved in the positive direction of the X axis. Further, the first coil 110 may be moved in the positive direction of the X axis, and the second coil 120 may be moved in the negative direction of the X axis.
  • only one of the first coil 110 and the second coil 120 may be moved.
  • the second method there can be cited a method of moving the first coil 110 and the second coil 120 in the vertical direction (height direction) up to a position where the UF-type induction heating device 100 is not liable to come into contact with the conductor plate S.
  • the first coil 110 is moved in the positive direction of the Z axis
  • the second coil 120 is moved in the negative direction of the Z axis.
  • only one of the first coil 110 and the second coil 120 may be moved.
  • the third method there is a method of turning the first coil 110 and the second coil 120 about a predetermined position of the side of the first coil 110 and the second coil 120 connected to the alternating-current power supply 200 as a turning axis until the UF-type induction heating device 100 no longer faces the plate surface of the conductor plate S each other.
  • Turning of the first coil 110 and the second coil 120 can be performed in a horizontal plane (X-Y plane in FIG. 1 ).
  • the direction of the turning axis in the case of performing the turning in a horizontal plane (X-Y plane in FIG. 1 ) results in the Z-axis direction.
  • first coil 110 and the second coil 120 may be the same or different in direction of turning in the case of performing the turning in a horizontal plane (X-Y plane in FIG. 1 ).
  • the direction of the turning axis in the case of performing the turning in a vertical plane (X-Z plane in FIG. 1 ) results in the Y-axis direction.
  • the direction of turning in the case of performing the tuning in a vertical plane (X-Z plane in FIG. 1 ) only needs to be a direction in which the first coil 110 and the second coil 120 each separate from the conductor plate S. Further, in the third method, only one of the first coil 110 and the second coil 120 may be turned.
  • a control device for moving the UF-type induction heating device 100 is also included in the induction heating system.
  • FIG. 6 is a view illustrating one example (actual measured values) of a distribution of surface temperatures of the conductor plate in the width direction (X-axis direction).
  • a steel plate was used as the conductor plate.
  • the distance from the center means the distance from the center position of the steel plate in the width direction (X-axis direction) in the case where measurement is performed along the width direction (X-axis direction) of the steel plate.
  • the center position of the steel plate in the width direction (X-axis direction) is set to 0 (zero).
  • FIG. 6 only a half of the width-direction (X-axis-direction) region of the steel plate is illustrated.
  • the present inventors performed each measurement in the case where the directions of alternating currents to be applied to the first coil 110 and the second coil 120 were set opposite like this embodiment and in the case where the directions of alternating currents to be applied to the first coil 110 and the second coil 120 were set the same like the TF-type induction heating device.
  • measurement conditions other than the directions of the alternating currents to be applied to the first coil 110 and the second coil 120 were set the same.
  • the concrete measurement conditions are as follows.
  • Effective permeability at a target heating temperature of the steel plate 80
  • a graph 601 indicates the result of the case where the directions of the alternating currents to be applied to the first coil 110 and the second coil 120 were set opposite.
  • a graph 602 indicates the result of the case where the directions of the alternating currents to be applied to the first coil 110 and the second coil 120 were set the same. In either case, at the center (center position in the width direction (X-axis direction)), the surface temperature of the steel plate increased to about 200[° C.].
  • the deviation of the surface temperature of the steel plate in the width direction (X-axis direction) was 2[° C.] (see the graph 601 ).
  • the surface temperature of the steel plate at the end portions (edge portions) in the width direction (X-axis direction) increased much higher than the other region and exceeded 1300[° C.] (see the graph 602 ).
  • the first coil 110 and the second coil 120 are faced each other across the conductor plate S so that the positions of the first coil 110 and the second coil 120 in the Y-axis direction (passing direction of the conductor plate S) become substantially the same. Then, the alternating currents at the frequency f at which the depth of penetration ⁇ of the current becomes equal to or less than half the plate thickness d of the conductor plate S are applied to the first coil 110 and the second coil 120 in opposite directions, thereby inductively heating the passing conductor plate S.
  • the UF-type induction heating device 100 can be formed of only the coils and the cores.
  • special structure members such as the conductor plate and the secondary coils for suppressing overheating of the width-direction end portions (edge portions) of the conductor plate S like the TF-type induction heating device.
  • the magnetic fields are generated in a direction vertical to the plate surface of the conductor plate S similarly to the TF-type induction heating device. Accordingly, it is possible to use the coils similar to those in the TF-type induction heating device as the first coil 110 and the second coil 120 .
  • temporary retraction is enabled easily without providing a mechanism for separating the coils. Further, since it is not necessary to provide a mechanism for separating the coils, it is possible to reduce a burden of a maintenance work of the coils.
  • the UF-type induction heating device 100 can be fabricated by using the TF-type induction heating device (the coils and the cores) and applying the currents opposite in direction to the coils as described previously. Accordingly, in the case where the TF-type induction heating device exists, the UF-type induction heating device 100 can be fabricated without greatly changing a facility.
  • the UF-type induction heating device 100 in this embodiment it is possible to suppress overheating of the width-direction end portions (edge portions) of the conductor plate S, and achieve two things, which are to uniformize the temperature distribution in the width direction of the conductor plate S as much as possible and to retract the coils temporarily with a simple constitution, without adding a special constitution for temporarily retracting the coils.
  • the magnetic fields that are the same in magnitude and opposite in direction are generated in regions where the conductor plate S does not exist between the first core 130 and the second core 140 (end portion regions in the width direction (X-axis direction) of the induction heating device 100 ) of a region between the first core 130 and the second core 140 . Accordingly, the magnetic fields in these regions are offset.
  • the UF-type induction heating device 100 it is possible to minimize the magnetic field that leaks to the surroundings around the UF-type induction heating device 100 , and it is also possible to suppress electromagnetic interference to the surroundings to the minimum.
  • a general induction heating device generates strong magnetic fields by coils and cores in the case where there is no conductor plate S being a load. For this reason, an inductance of the induction heating device increases. Thus, when an alternating current starts being applied to the coil, voltages at both ends of the coil increase rapidly. Therefore, in the case where there is no conductor plate S, it is not easy to apply the alternating current to the coil up to a rated current of the induction heating device, and thus it is sometimes impossible to confirm soundness of a power supply system beforehand.
  • the magnetic fields are offset to almost disappear in the region other than the region between the first coil 110 and the second coil 120 .
  • the inductance of the UF-type induction heating device 100 is close to 0 (zero), and even in a state where there is no conductor plate S, it is possible to apply the current to the first coil 110 and the second coil 120 up to a rated current of the UF-type induction heating device 100 .
  • the inductance is small as compared to a general induction heating device even when the conductor plate S is being heated. For this reason, as compared to a general induction heating device, it is possible to reduce the voltage to be applied to the both ends of the coils (first coil 110 and the second coil 120 ). Thus, it is possible to suppress a capacity of the alternating-current power supply 200 . Further. a burden of an insulating treatment on the first coil 110 and the second coil 120 is reduced. Further, it is possible to suppress trouble caused by discharge of the first coil 110 and the second coil 120 .
  • the upper end surfaces and the lower end surfaces of the first coil 110 and the second coil 120 when viewed along the passing direction of the conductor plate S are made flat. Further, upper end surfaces and lower end surfaces of the first core 130 and the second core 140 when viewed along the passing direction of the conductor plate S are also made flat in conformity with the first coil 110 and the second coil 120 .
  • FIG. 7 is a view conceptually illustrating one example of the relationship between the position of the conductor plate S in the plate thickness direction and current densities of the eddy currents Ie 1 , Ie 2 flowing through the conductor plate S.
  • the eddy current Ie 1 flows through the one surface (upper surface) of the conductor plate S
  • the eddy current Ie 2 flows through the other surface (lower surface) of the conductor plate S in a direction opposite to the eddy current Ie 1 (see the left drawing in FIG. 7 ).
  • the depth of penetration ⁇ of the eddy currents Ie 1 , Ie 2 is the thickness d of the conductor plate S, as illustrated in the left drawing in FIG.
  • the current densities of the eddy currents Ie 1 , Ie 2 are not constant in the plate thickness direction of the conductor plate S and become smaller as it goes farther from the surface.
  • the frequency (f in (1) Expression) of the alternating currents to be applied to the first coil 110 and the second coil 120 so that the depth of penetration ⁇ of the current in the conductor plate S becomes equal to or less than (or less than) the plate thickness d [m] of the conductor plate S, for example. That is, in place of (1) Expression, the condition of ⁇ d or ⁇ d may be employed.
  • the single alternating-current power supply 200 applies the alternating currents to the first coil 110 and the second coil 120 .
  • the number of alternating-current power supplies is not limited to one as long as the directions of the magnetic fields generated by the alternating currents flowing through the first coil 110 and the second coil 120 are designed to be opposite to each other.
  • FIG. 8 is a view illustrating a first modified example of the constitution of the induction heating system. Concretely, FIG. 8 is a view illustrating the state of an induction heating device 100 viewed from above.
  • the induction heating system includes an UF-type induction heating device 100 , alternating-current power supplies 210 , 220 , and a control device 230 .
  • the UF-type induction heating device 100 is the same as that illustrated in FIG. 1 .
  • the alternating-current power supplies 210 , 220 are the same as the alternating-current power supply 200 illustrated in FIG. 1 .
  • One end portion 111 of a first coil 110 is electrically connected to one terminal 211 of two output terminals of the alternating-current power supply 210
  • the other end portion 112 of the first coil 110 is electrically connected to the other terminal 212 of the two output terminals of the alternating-current power supply 210 .
  • One end portion 121 of a second coil 120 is electrically connected to one terminal 221 of two output terminals of the alternating-current power supply 220 , and the other end portion 122 of the second coil 120 is electrically connected to the other terminal 222 of the two output terminals of the alternating-current power supply 220 .
  • the alternating-current power supplies 210 , 220 operate in synchronization with each other. That is, the alternating-current power supplies 210 , 220 apply alternating currents having the same waveform at the same frequency to the first coil 110 and the second coil 120 respectively at the time same. However, the directions of the alternating currents flowing through mutually facing regions of the first coil 110 and the second coil 120 (at the same time) are designed to be opposite to each other.
  • the control device 230 controls output timings in the alternating-current power supplies 210 , 220 in order for the alternating-current power supplies 210 , 220 to operate in synchronization with each other as above.
  • the two alternating-current power supplies are designed only to synchronize, for example, they may be connected to the first coil 110 and the second coil 120 one by one individually.
  • FIG. 8 there has been explained, as an example, the case where the two alternating-current power supplies 210 , 220 are arranged at one end portion side (positive direction side of the X axis) of width-direction end portions of the conductor plate S.
  • the alternating-current power supply 210 that applies the current to the first coil 110 at one end portion side (positive direction side of the X axis) of the width-direction end portions of the conductor plate S and arrange the alternating-current power supply 220 that applies the current to the second coil 120 at the other end portion side (negative direction side of the X axis) of them.
  • the second coil 120 illustrated in FIG. 8 is arranged in a state of being turned by 180° in an X-Y plane (namely about the Z axis as a turning axis).
  • the single alternating-current power supply 200 applies the alternating currents in parallel to the first coil 110 and the second coil 120 .
  • the single alternating-current power supply 200 may apply the alternating currents in series to the first coil 110 and the second coil 120 .
  • FIG. 9 is a view illustrating a second modified example of the constitution of the induction heating system. Concretely, FIG. 9 is a view illustrating the state of an induction heating device 900 viewed from above.
  • the induction heating system includes an UF-type induction heating device 900 , and an alternating-current power supply 200 .
  • the UF-type induction heating device 900 includes a first coil 910 , a second coil 920 , a first core 130 , and a second core 140 .
  • the first core 130 and the second core 140 are the same as those illustrated in FIG. 1 .
  • the first coil 910 and the second coil 920 are coupled by the other end portion 112 of the first coil 110 and the one end portion 121 of the second coil 120 , which are illustrated in FIG. 1 .
  • the first coil 910 and the second coil 920 and the first coil 110 and the second coil 120 are the same.
  • One end portion 111 of the first coil 910 is electrically connected to one terminal 201 of two output terminals of the alternating-current power supply 200
  • the other end portion 122 of the second coil 920 is electrically connected to the other terminal 202 of the two output terminals of the alternating-current power supply 200 .
  • the first coil 910 and the second coil 920 are directly connected, and the single alternating-current power supply 200 can apply the alternating current to the first coil 910 and the second coil 920 in series.
  • the UF-type induction heating device 900 is retracted temporarily to the positive direction side of the X axis.
  • the conductor plate S is longer in the width direction (X-axis direction) than in the passing direction (Y-axis direction).
  • the conductor plate S becomes longer in the passing direction (Y-axis direction) than in the width direction (X-axis direction).
  • the shape of a cross section vertical to the flowing direction of the alternating current from the alternating-current power supply 200 which is the shape of the first coil 110 and the second coil 120
  • a shape may be another shape such as a hollow circular shape or a hollow elliptical shape.
  • the first coil 110 and the second coil 120 do not need to have a hollow shape.
  • the method of cooling the first coil 110 and the second coil 120 may be an air cooling method, an external water cooling method, or a combined method of the respective cooling methods.
  • first core 130 and the second core 140 makes it possible to increase the magnitude of the magnetic fields to be applied to the conductor plate S, and this makes it possible to improve the heating efficiency of the conductor plate S, and thus it is preferred. Further, use of the first core 130 and the second core 140 makes it possible to suppress the electromagnetic interference to the surroundings of the UF-type induction heating device 100 , and thus it is preferred. However, it is not always necessary to use the first core 130 and the second core 140 .
  • the UF-type induction heating device is constituted without using the first core 130 and the second core 140 .
  • the number of turns of each of the first coil 110 and the second coil 120 is one [time] (one turn).
  • the number of turns of each of the first coil 110 and the second coil 120 may be two [times] or more.
  • the single UF-type induction heating device 100 is arranged for the conductor plate S.
  • the single UF-type induction heating device 100 fails to increase the temperature of the conductor plate S up to a desired temperature due to the capacity shortage of the alternating-current power supply 200 , for example.
  • there is sometimes a case that there is no installation space of the UF-type induction heating device 100 to thus make it impossible to arrange the large-sized UF-type induction heating device 100 .
  • a temperature pattern of the conductor plate S is restricted and the temperature pattern needs a plurality of temperature increasing processes.
  • a plurality of the UF-type induction heating devices 100 may be arranged parallel to the passing direction of the conductor plate S.
  • each one alternating-current power supply 200 can be connected to each of the UF-type induction heating devices 100 . It is not necessary for these plural alternating-current power supplies 200 to equalize at least one of their voltages, currents, and frequencies. Further, the number of turns of the coils and the material of the coils may be changed in each induction heating device. Further, when the capacity of the alternating-current power supply 200 is large, it is also possible to connect this alternating-current power supply 200 to the plural UF-type induction heating devices 100 .
  • one first core and one second core are each provided, a plurality of first coils and a plurality of second coils are provided in the first core and the second core respectively, and the first coils and the second coils are each arranged parallel to the passing direction of the conductor plate S.
  • FIG. 10 is a view illustrating a third modified example of the constitution of the induction heating system.
  • FIG. 10 is a view illustrating the state of an induction heating device 1000 viewed from above.
  • the induction heating system includes an UF-type induction heating device 1000 , and alternating-current power supplies 210 , 220 .
  • the UF-type induction heating device 1000 includes two first coils 1110 , 1130 , two second coils 1120 , 1140 , a first core 1150 , and a second core 1160 .
  • the first coils 1110 , 1130 and the second coils 1120 , 1140 are the same as the first coil 110 and the second coil 120 illustrated in FIG. 1 .
  • the alternating-current power supplies 210 , 220 are the same as the alternating-current power supply 200 illustrated in FIG. 1 .
  • FIG. 11 is a view illustrating one example of a Y-Z cross section of the UF-type induction heating device 1000 in the third modified example.
  • FIG. 11 is a view corresponding to FIG. 2 .
  • the first core 1150 and the second core 1160 are cores that are the same in material, shape, and size.
  • the first core 1150 and the second core 1160 are each formed of a soft magnetic material such as ferrite, for example, similarly to the first core 130 and the second core 140 illustrated in FIG. 1 .
  • the first core 1150 has a shape obtained by forming recessed portions in a rectangular parallelepiped shape according to shapes of regions extending in the width direction (X-axis direction) of the first coils 1110 , 1130 .
  • the recessed portions of the first core 1150 are formed so that in the case where the first coils 1110 , 1130 are arranged in the recessed portions, the surfaces of the first coils 1110 , 1130 facing the conductor plate S and the surfaces of the first core 1150 facing the conductor plate S become substantially flush with each other.
  • the second core 1160 has a shape obtained by forming recessed portions in a rectangular parallelepiped shape according to shapes of regions extending in the width direction (X-axis direction) of the second coils 1120 , 1140 . Further, the recessed portions of the second core 1160 are formed so that in the case where the second coils 1120 , 1140 are arranged in the recessed portions, the surfaces of the second coils 1120 , 1140 facing the conductor plate S and the surface of the second core 1160 facing the conductor plate S become substantially flush with each other.
  • one end portion 1111 of the first coil 1110 is electrically connected to one terminal 211 of two output terminals of the alternating-current power supply 210 . Further, the other end portion 1112 of the first coil 1110 is electrically connected to the other terminal 212 of the two output terminals of the alternating-current power supply 210 .
  • one end portion 1121 at a position facing the other end portion 1112 of the first coil 1110 each other in the Z-axis direction is electrically connected to the one terminal 211 of the two output terminals of the alternating-current power supply 210 .
  • the other end portion 1122 at a position facing the one end portion 1111 of the first coil 1110 each other in the Z-axis direction is electrically connected to the other terminal 212 of the two output terminals of the alternating-current power supply 210 .
  • one end portion 1131 of the first coil 1130 is electrically connected to one terminal 221 of two output terminals of the alternating-current power supply 220 . Further, the other end portion 1132 of the first coil 1130 is electrically connected to the other terminal 222 of the two output terminals of the alternating-current power supply 220 .
  • one end portion 1141 at a position facing the other end portion 1132 of the first coil 1130 each other in the Z-axis direction is electrically connected to the one terminal 221 of the two output terminals of the alternating-current power supply 220 .
  • the other end portion 1142 at a position facing the one end portion 1130 of the first coil 1130 each other in the Z-axis direction is electrically connected to the other terminal 222 of the two output terminals of the alternating-current power supply 220 .
  • first coil 1110 and the second coil 1120 are connected in parallel to the alternating-current power supply 210 so that the turning direction of the first coil 1110 and the turning direction of the second coil 1120 , (which are viewed from the alternating-current power supply 210 ), become opposite to each other.
  • first coil 1130 and the second coil 1140 are connected in parallel to the alternating-current power supply 220 so that the turning direction of the first coil 1130 and the turning direction of the second coil 1140 , (which are viewed from the alternating-current power supply 220 ), become opposite to each other.
  • the alternating-current power supply 210 applies alternating currents, as illustrated in FIG. 10
  • the directions of the alternating currents flowing through mutually facing regions of the first coil 1110 and the second coil 1120 become opposite to each other (see arrow lines illustrated in the first coil 1110 and the second coil 1120 in FIG. 10 ).
  • the alternating-current power supply 220 applies alternating currents, as illustrated in FIG. 10
  • the directions of the alternating currents flowing through mutually facing regions of the first coil 1130 and the second coil 1140 become opposite to each other (see arrow lines illustrated in the first coil 1130 and the second coil 1140 in FIG. 10 ).
  • FIG. 10 there has been explained, as an example, the case where the directions of the alternating currents (at the same time) flowing through the two first coils 1110 , 1130 arranged in parallel to the passing direction of the conductor plate S are the same and the directions of the alternating currents (at the same time) flowing through the two second coils 1120 , 1140 arranged in parallel to the passing direction of the conductor plate S are the same.
  • the directions of the alternating currents (at the same time) flowing through the first coils 1110 , 1130 and the directions of the alternating currents (at the same time) flowing through the second coils 1120 , 1140 may be opposite.
  • the upper end surfaces and the lower end surfaces of the first coil 110 and the second coil 120 when viewed along the passing direction of the conductor plate S are preferably made flat.
  • the upper end surfaces and the lower end surface of the first coil and the second coil when viewed along the passing direction of the conductor plate S are not limited to being flat.
  • the upper end surfaces and the lower end surfaces of the first coil and the second coil when viewed along the passing direction of the conductor plate S may be a smooth curved surface or bent surface so that the distance between the first coil and the conductor plate S and the distance between the second coil and the conductor plate S become longer as it is at a position closer to the center of the conductor plate S when viewed along the passing direction of the conductor plate S, for example.
  • the upper end surfaces and the lower end surfaces of the first coil and the second coil when viewed along the passing direction of the conductor plate S may be a smooth curved surface or bent surface so that the distance between the first coil and the conductor plate S and the distance between the second coil and the conductor plate S become shorter as it is at a position closer to the center of the conductor plate S when viewed along the passing direction of the conductor plate S, for example.
  • upper end surfaces and lower end surfaces of the cores when viewed along the passing direction of the conductor plate S can be set to a smooth curved surface or bent surface according to shapes of the first coil and the second coil.
  • the present invention can be utilized for induction heating of a conductor plate.

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JP6991753B2 (ja) * 2017-06-30 2022-01-13 高周波熱錬株式会社 加熱コイル及び加熱方法
JP6866410B2 (ja) * 2019-02-20 2021-04-28 島田理化工業株式会社 トンネル型加熱コイルを用いた誘導加熱方法
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